Atomic beam experiments are limited by intensity. Intensity limitations are specially critical in the measurements of metastable atoms, since their relative population is several order of magnitude smaller than the beam population. This thesis provides a method for increasing the intensity of metastable argon and neon beams effusing from a hot cathode, glow discharge by use of a longitudinal magnetic field. The argon and neon metastable atom intensities have been measured for a range of discharge pressure, voltage, and current for a magnetic field strengths from 0 to 31 mT. For both argon and neon, the metastable atom beam intensity rises to a maximum value about one order of magnitude above the zero field case. A qualitative discussion of the theory of this phenomenon is also presented.

The cylindrical column of plasma produced in the first stage of a z-pinch discharge is theoretically unstable. For one particular type of instability, the amplitude of a surface perturbation increases at a rate dependent on the acceleration of the surface (Rayleigh-Taylor instabilities). An experimental study of these instabilities has been carried out by photographing the discharge column with a high-speed framing-camera. Simple rotationally symmetric instabilities have been excited in the normally stable initial stage of an argon z-pinch discharge by means of a set of equally spaced glass rings. The framing camera photographs show that the instabilities develope approximately in accordance with the Rayleigh-Taylor theory. No axial drift of the instabilities is observed, but the new technique of studying instabilities reveals that the acceleration of the discharge boundary changes appreciably three or four times during the initial stage of the discharge. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Electromagnetic shock tubes were used to generate plasmas having a number density of the order of 10¹⁷ per cm³ and an energy per particle of 1-3 ev. In the shock tubes employed, the driving current was passed via electrodes through a discharge at one end of the tube. The discharge gases that were driven down the shock tube plus the ambient gas that was picked up and heated constituted the plasma that was studied. Many workers have assumed that shock equations can describe the discontinuity at the front of the plasma. An investigation into the effects of changes in the geometry of the driver mechanism has disclosed that the luminosity structure that can be attributed to the discharge gases stays very close to the luminosity front. The amount of ambient gas that is entrained in front of the discharge gases is thus small. Therefore, some doubt exists about the applicability of the shock equations both in the present shock tube and in the electromagnetic shock tubes of other workers. The shape of the luminosity front of the plasma was found to be affected by the properties of the driving discharge, even at a time long after the driving current had ceased to flow. Instabilities of the discharge and contamination by electrode material were found to drastically affect the homogeneity of the plasma. The homogeneity and reproducibility of the plasma produced by a small-cathode driver were found to be fairly good. However, there was a large amount of contamination in the plasma. The plasma was used to investigate the electro-dynamic response of an inductive magnetohydrodynamic power generator. Expressions for the output power were derived and compared with the experimental results. The electrodynamical response of a novel electrode-type Bɵ magnetohydrodynamic power generator was calculated. In an experiment performed with this generator a magnetohydrodynamic Interaction was observed indicating that the plasma was transporting an azimuthal magnetic field. No output power was obtained. The probable cause for this was that the applied magnetic field was insufficient to break down the sheath on the electrodes. A low pressure spark gap switch suitable for use as a main switch and as a "crowbar" switch on a capacitor bank was developed. The switch was operated over a voltage range of 0.5 to 25 kV, at energies up to 4 kJ and currents up to 500 kA. Under normal operating conditions the triggering time was 40 nsec and the jitter approximately 10 nsec. The inductance of the main switch was 4 nH and the inductance of the crowbar switch was about 1 nH. Other contributions are presented on a wide-voltage-range open-air spark gap switch, high voltage trigger circuits and on the dynamics of the plasma in an electromagnetic shock tube. The latter consists of an elementary treatment of the electromagnetic acceleration processes and a proposal of a model for the decelerating plasma. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

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published_or_final_version / Electrical Engineering / Master / Master of Philosophy

Thesis (PhD (Electrical Engineering))--Cape Peninsula University of Technology, 2018. / The generation of electricity through the conventional conversion system such as thermal and hydroelectric plants may no longer be sufficient to meet the increasing demands and usage. One of the major reasons for shortage supply of electric power is due to the lack of fossil fuel and other conventional resources that are currently being used in Africa. In addition, the conversion process of the conventional system often causes pollution which contributes to global warming. Therefore, there is a need for this research to develop novel and alternative methods of generating electric power. Among these methods is the Magnetohydrodynamics (MHD) conversion system, which is a direct energy conversion system. In this system, plasma or ionised gas is directly converted into electric power with generating efficiency of about 62 %. The conversion process of the MHD system is based on the principle of Faraday’s Law of electromagnetism and fluid dynamics. The focus of the present study is to investigate alternative methods through which an MHD power generator can be coupled to the existing thermal plants in South Africa. In doing so, the thermal cycle efficiency of these conventional plants can be improved. Another goal of this study is to investigate the behaviour of an MHD generator prototype under exposure to plasma through simulation and experimentation in a laboratory setting.

Sanborn C. Brown. / "July 25, 1955." "This report is identical with material prepared for Handbuch der Physik, Volume XXII, 1955." / Includes bibliographical references. / Army Signal Corps Contract DA36-039 sc-42607 Project 132B Dept. of the Army Project 3-99-12-022

W.P. Allis [and] Sanborn C. Brown. / "April 23, 1952." / Bibliography: p. 13. / Army Signal Corps Contract No. DA 36-039 sc 100. Project no. 8-102B-0. Dept. of the Army Project no. 3-99-10-022.

A.D. McDonald, Sanborn C. Brown. / "August 3, 1949." / Bibliography: p. 6. / Army Signal Corps Contract No. W36-039-sc-32037 Project No. 102B Dept. of the Army Project No. 3-99-10-022